Expand section on finding parallel edges

[krlawrence]

The examples that are used to explore parallel edge detection return results in terms of vertex pairs. It would be good to add examples that return the actual edges instead. A simple example would be to add a duplicate edge between SAF (44) and DFW (8) and then run the query below.

gremlin> g.addE('route').from(V(44)).to(V(8))
==>e[60867][44-route->8]
gremlin> g.V(44).outE().group().by().by(inV().path().by().by(label)).unfold().group().by(values).by(select(keys).fo
ld()).unfold()
==>path[v[44], route, v[13]]=[e[5020][44-route->13]]
==>path[v[44], route, v[8]]=[e[60867][44-route->8], e[5019][44-route->8]]
==>path[v[44], route, v[20]]=[e[5021][44-route->20]]
==>path[v[44], route, v[31]]=[e[5022][44-route->31]]   

gremlin> g.V(44).outE().group().by().by(inV().path().by().by(label)).unfold().group().by(values).by(select(keys).fo
ld()).unfold().filter(select(values).count(local).is(gt(1)))
==>path[v[44], route, v[8]]=[e[60867][44-route->8], e[5019][44-route->8]]